heme 3 Flashcards
Vitamin K deficiency labs
PT + INR prolonged + PTT normal or mildly prolonged (prolonged with severe vitamin k deficiency) + inciting factor
what is d-dimer?
fibrin degradation product (or FDP), a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis
Other reasons for elevated d-dimer
any acute or inflammatory process (eg, age >50 years, recent surgery or trauma, acute illness, pregnancy or postpartum state, rheumatologic disease, renal dysfunction [estimated glomerular filtration rate <60 mL/min/1.73 m2]), sickle cell disease, pulmonary disease
life span of one red blood cell
120 days
effect of prophylactic heparin on PTT
small, but significant, increase in aPTT (mean 38.6)
lab profile of factor VIII deficiency
Prolonged PTT
Effect of warfarin on PT and PTT
Typically prolongs the PT alone, but at high levels can prolong both tests.
Effect of heparin on PT and PTT
Heparin typically prolongs the aPTT alone (because PT reagents contain heparin-binding agents that block heparin effect), but at high levels heparin can prolong both tests.
Effect of direct thrombin inhibitors on PT and PTT
typically prolong both tests
Effect of Xa inhibitors on PT and PTT
prolong the PT and aPTT, although these effects are variable
Effect of liver disease on PT and PTT
Typically prolongs just PT, but also prolong PTTs in severe liver disease
Describe the clotting cascade
https://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Coagulation_full.svg/400px-Coagulation_full.svg.png
what is a lupus anticoagulant (pathophys)
- Acquired autoantibody to phospholipids. Interacts with platelet membrane phospholipids, increasing adhesion and aggregation of platelets, which accounts for in vivo prothrombotic characteristics.
- misnomer, as it is actually a prothrombotic antibody.
Initial workup of prolonged PTT
Step 1 = Mixing study →
IF corrects = deficient clotting factor
IF remains abnormal = inhibitor present (ie lupus anticoagulant)
confirm presence with prolonged phospholipid-sensitive functional clotting testing (dilute Russell’s viper venom time, or the Kaolin clotting time)
Concept of a mixing study
You’re looking for an inhibitor in plasma or a deficient clotting factor. Patient’s plasma is mixed with normal pooled plasma and the clotting is reassessed. If a clotting inhibitor such as a lupus anticoagulant is present, the inhibitor will interact with the normal pooled plasma and the clotting time will remain abnormal. However, if the clotting time of the mixed plasma corrects towards normal, the presence of an inhibitor such as the lupus anticoagulant is excluded, and instead a deficient quantity of clotting factor (that is replenished by the normal plasma) is likely.
treatment of lupus anticoagulant
IF history of thrombosis + documented history of lupus anticoagulant twice → consider indefinite AC
IF no history of thrombosis → observation
Prevalence of lupus anticoagulant
Relatively common (believed to be approximately 5% in adults, with a predominance among females of reproductive age).
Why does renal disease cause coagulopathy
uremic platelet dysfunction
Reversal agent for Xa inhibitors
Andexxa
Problem with Xa inhibitor reversal agent
Not available on most pharmacy formularies
Thrombotic risk of liver disease
Cirrhotics are coagulopathic but also hypercoagulable (protein c and s deficiency). This is why they still need heparin dvt ppx (from studies).
Only case in which hypercoagulability workup would change management
High risk anti phospholipid syndrome, which requires coumadin
Where are platelets produced?
Bone marrow, just like red and white cells.
What is “treatment failure” from NOACs typically due to?
Nonadherence – patients missing doses. Due to short half life, you are at increased thrombotic risk by just missing a dose or two.
Why you always need to calculate reticulocyte index
The problem arises because the reticulocyte count is not really a count but rather a percentage: it reports the number of reticulocytes as a percentage of the number of red blood cells. In anemia, the patient’s red blood cells are depleted, creating an erroneously elevated reticulocyte count.
What type and screen generally screens for
ABO
Rh
some other atypical antibodies
typical premedication before IVIG
acetaminophen and diphenhydramine
IVIG side effect profile
can have severe adverse effects, both localized and systemic.
What are hemagglutinins?
glycoproteins which cause red blood cells (RBCs) to agglutinate or clump together. (Note that agglutination is one of three steps in the more complex process of coagulation.)
- anti-A and anti-B antibodies are considered hemagluttinins
May Thurner Syndrome
Iliac vein compression syndrome. compression of the common venous outflow tract of the left lower extremity may cause discomfort, swelling, pain or clotting in the iliofemoral veins. It is caused by left common iliac vein compression by the overlying right common iliac artery.
Evans syndrome clinical features
AIHA + thrombocytopenia
When do schistocytes occur in hemolytic syndromes
intravascular syndromes
examples of intravascular hemolysis
1) prosthetic valves
2) MAHA — microangiopathic hemolytic anemia (TTP, HUS, DIC)
First step on boards if stem sounds like TTP
peripheral smear (don’t send ADAMST13 level, takes too long)
Risk for spontaneous brain bleed happens at what platelet level
10
How to exclude pseudo thrombocytopenia
Draw blood into citrated tube rather than EDTA tube
First step on boards if looks like ITP and platelets aren’t severely low
Repeat CBC outpatient
Next step after SPEP shows polyclonal gammopathy
NO FURTHER TESTING
Differential for polyclonal gammopathy
Inflammatory disorders
Infections
Liver disease (60%)
Reactive processes
EPO should be avoided in…
patients with a curable malignancy
Presentation of hemoglobin C trait
- asymptomatic
Presentation of hemoglobin C disease
- mild hemolytic anemia, splenomegaly, borderline anemia
how to differentiate Hgb C from hgb A2 disease
- citric acid agar
Second most common cause of enzyme-deficient hemolytic anemia after G6PD
Pyruvate kinase deficiency (PKD)
Management of PKD
most affected individuals don’t need treatment
PKD inheritance
Autosomal recessive
Clinical features of Hbs-Beta thalassemia
- typically clinically indistinguishable from SCD
electrophoresis pattern of SCD
- pretty much all HbS, no HbA
RDW in thalassemia
- typically low (red cells are homogeneous)
Lab test to distinguish thalassemia from iron deficiency aside from electrophoresis
ZPP (zinc protoporphyrin)
How to diagnosis alpha-thalassemia trait
- NOT electrophoresis
- sequencing
RBC count in mild thalassemia
- commonly normal or elevated (unclear reason)
Management of drug induced AIHA
- stop drug and supportive care (not immunosuppression)
Most common cause of drug-induced AIHA
cephalosporins
hereditary elliptocytosis clinical features
hemolytic anemia (defect in RBC membrane protein and cytoskeleton that predisposes a pt to hemolytic anemia)
sequela of copper deficiency
sideroblastic anemia
clinical features of copper deficiency
sensory ataxia + neuropathy + muscle weakness
C3 and IgG pattern most commonly seen with warm AIHA
IgG+, C3+
antibody patter for cold agglutinin disease
IgG negative C3 positive
Pyruvate kinase deficiency clinical presentations
- neonatal janducie
- chronic hemolytic anemia
- iron overload
- coombs negative hemolytic anemia
what is transient erythroblastopenia of childhood? clinical features?
- transient or temporary red cell aplasia (self limiting)
- otherwise healthy child abruptly develops severe anemia
MCV in anemia from hypothyroidism
macrocytosis
